There is a mining drill in the java version already. I guess we will get this tool also in unity.
A mining machine /vehicle would be awesome
Having a dedicated railway machine would be awesome. If we can program it to dig out a certain pattern it would be helpful, just like in the Minecraft Turtle mod with Redstone Power. Traincraft may have had this also digging tunnels for you, while the real world one would dig, place foundation, and even place the rails afterward.